erosion and deposition by glaciers

erosion by valley glaciers

Valley glaciers form several unique features through erosion. You can see some of them in Figure 10.28. As a valley glacier flows through a V-shaped river valley, it scrapes away the sides of the valley. It carves a U-shaped valley with nearly vertical walls. A line called the trimline shows the highest level the glacier reached. A cirque is a rounded hollow carved in the side of a mountain by a glacier. The highest cliff of a cirque is called the headwall. An arte is a jagged ridge that remains when cirques form on opposite sides of a mountain. A low spot in an arte is called a col. A horn is a sharp peak that is left behind when glacial cirques are on at least three sides of a mountain.

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deposition by glaciers

Glaciers deposit their sediment when they melt. They drop and leave behind whatever was once frozen in their ice. Its usually a mixture of particles and rocks of all sizes, called glacial till. Water from the melting ice may form lakes or other water features. Figure 10.29 shows some of the landforms glaciers deposit when they melt. Moraine is sediment deposited by a glacier. A ground moraine is a thick layer of sediments left behind by a retreating glacier. An end moraine is a low ridge of sediments deposited at the end of the glacier. It marks the greatest distance the glacier advanced. A drumlin is a long, low hill of sediments deposited by a glacier. Drumlins often occur in groups called drumlin fields. The narrow end of each drumlin points in the direction the glacier was moving when it dropped the sediments. An esker is a winding ridge of sand deposited by a stream of meltwater. Such streams flow underneath a retreating glacier. A kettle lake occurs where a chunk of ice was left behind in the sediments of a retreating glacier. When the ice melted, it left a depression. The meltwater filled it to form a lake.

how glaciers form

Glaciers form when more snow falls than melts each year. Over many years, layer upon layer of snow compacts and turns to ice. There are two different types of glaciers: continental glaciers and valley glaciers. Each type forms some unique features through erosion and deposition. An example of each type is pictured in Figure 10.27. A continental glacier is spread out over a huge area. It may cover most of a continent. Today, continental glaciers cover most of Greenland and Antarctica. In the past, they were much more extensive. A valley glacier is long and narrow. Valley glaciers form in mountains and flow downhill through mountain river valleys.

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erosion by glaciers

Like flowing water, flowing ice erodes the land and deposits the material elsewhere. Glaciers cause erosion in two main ways: plucking and abrasion. Plucking is the process by which rocks and other sediments are picked up by a glacier. They freeze to the bottom of the glacier and are carried away by the flowing ice. Abrasion is the process in which a glacier scrapes underlying rock. The sediments and rocks frozen in the ice at the bottom and sides of a glacier act like sandpaper. They wear away rock. They may also leave scratches and grooves that show the direction the glacier moved.

instructional diagrams

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This diagram shows about Erosion and Deposition by Glaciers. Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to move. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be dozens or even hundreds of kilometers long. Presently, glaciers occupy about 10 percent of the world's total land area, with most located in polar regions like Antarctica, Greenland, and the Canadian Arctic. Most glaciers lie within mountain ranges. Glaciers cause erosion by plucking and abrasion. Glaciers deposit their sediment when they melt. Landforms deposited by glaciers include drumlins, kettle lakes, and eskers. A ground moraine is a thick layer of sediments left behind by a retreating glacier. A drumlin is a long, low hill of sediments deposited by a glacier. Drumlins often occur in groups called drumlin fields. An esker is a winding ridge of sand deposited by a stream of meltwater. A kettle lake occurs where a chunk of ice was left behind in the sediments of a retreating glacier. When the ice melted, it left a depression. The meltwater filled it to form a lake.

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The diagram shows several features of an alpine glacier. Glaciers are masses of flowing ice that are formed when more snow falls than melts each year. Snow falls in the accumulation zone, usually the part of the glacier with the highest elevation. Further down the glacier, usually at a lower altitude, is the ablation area, where most of the melting and evaporation occur. At locations where a glacier flows rapidly, friction creates giant cracks called crevasse. Moraines are created when the glacier pushes or carries rocky debris as it moves. Medial moraines run down the middle of a glacier, lateral moraines along the sides, and terminal moraines are found at the terminus of a glacier. Glaciers cause erosion by plucking and abrasion. Valley glaciers form several unique features through erosion, including cirques and artes. Glaciers deposit their sediment when they melt. Landforms deposited by glaciers include drumlins, kettle lakes, and eskers.

questions

Glaciers presently cover about 40 percent of Earths surface.

a. true

-->  b. false

Continental glaciers are long and narrow.

a. true

-->  b. false

Valley glaciers flow downhill through river valleys.

-->  a. true

b. false

Continental glaciers form cirques and horns.

a. true

-->  b. false

A glacier picks up sediments when they freeze to ice at the bottom of the glacier.

-->  a. true

b. false

The narrow end of a drumlin points in the direction that the glacier moved.

-->  a. true

b. false

All glaciers move because of gravity.

-->  a. true

b. false

The main way glaciers cause erosion is by ice wedging.

a. true

-->  b. false

Glaciers are getting smaller because of global warming.

-->  a. true

b. false

The valley carved by a mountain glacier has gently sloping walls.

a. true

-->  b. false

rounded hollow carved in the side of a mountain by a glacier

a. continental glacier

b. arte

c. esker

-->  d. cirque

e. valley glacier

f. horn

g. drumlin

type of glacier that is spread out over a large area

-->  a. continental glacier

b. arte

c. esker

d. cirque

e. valley glacier

f. horn

g. drumlin

long low hill of sediments deposited by a glacier

a. continental glacier

b. arte

c. esker

d. cirque

e. valley glacier

f. horn

-->  g. drumlin

type of glacier that forms in mountains

a. continental glacier

b. arte

c. esker

d. cirque

-->  e. valley glacier

f. horn

g. drumlin

winding ridge of sand deposited by a stream of meltwater

a. continental glacier

b. arte

-->  c. esker

d. cirque

e. valley glacier

f. horn

g. drumlin

jagged ridge that remains when two cirques form on opposite sides of a mountain

a. continental glacier

-->  b. arte

c. esker

d. cirque

e. valley glacier

f. horn

g. drumlin

sharp peak that is left behind when glaciers erode all sides of a mountain

a. continental glacier

b. arte

c. esker

d. cirque

e. valley glacier

-->  f. horn

g. drumlin

Today, continental glaciers cover most of

a. Alask

b. Canada.

-->  c. Greenland.

d. all of the above

Features caused by valley glacier erosion include

a. eskers.

-->  b. cirques.

c. drumlins.

d. end moraines.

A trimline shows the

-->  a. highest level a valley glacier reached.

b. direction in which a glacier traveled.

c. greatest distance a glacier advanced.

d. ending edge of a continental glacier.

A headwall is the

a. starting point of a continental glacier.

b. highest ridge of an esker.

-->  c. highest cliff of a cirque.

d. low spot in an arte.

A valley glacier changes a V-shaped river valley to a

a. kettle lake.

b. drumlin field.

-->  c. U-shaped valley.

d. meltwater stream.

A thick layer of sediments left behind by a retreating continental glacier is called

-->  a. ground moraine.

b. end moraine.

c. glacial till.

d. none of the above

The last time glaciers dipped as far south as Chicago and New York City was

a. 10 million years ago.

b. 1 million years ago.

c. 120,000 years ago.

-->  d. 12,000 years ago.

diagram questions

question_image

Which structure marks the greatest distance the glacier advanced?

-->  a. Moraine

b. Zone of ablation

c. Snout

d. Zone of accumulation

question_image

What is between the Zone of ablation and Moraine?

a. continental glacier

b. glacial till

c. Zone of Accumulation

-->  d. Snout

question_image

How many zones are depicted in the diagram?

a. 4

b. 1

c. 3

-->  d. 2

question_image

The shape of which area could be caused by melting or an avalanche?

a. moraine

-->  b. zone of ablation

c. snout

d. zone of accumulation

question_image

Which part of the diagram is most likely to deposit sediment?

a. C

b. E

c. A

-->  d. B

question_image

The Compressing Flow is above:

a. The Bergschrund.

b. the Accumulation Zone.

c. The Crevasses.

-->  d. the Extending Flow.

question_image

How many zones can you see?

a. 1

-->  b. 2

c. 9

d. 5

question_image

Identify the highest layer.

a. Floodplai

-->  b. Receding Glacier

c. drumlin

d. esker

question_image

What is between the kame and the floodplain?

a. drumlin

b. receding glacier

-->  c. terminal moraine

d. esker

question_image

Where do glaciers deposit their sediment?

a. ground moraine

b. receding glacier

-->  c. Drumlin, kettles, and esker

d. rock bed

question_image

How many parts are shown in the diagram below?

a. 5

b. 2

c. 3

-->  d. 9

question_image

A thick layer of sediments is left behind by a retreating glacier. What is it known as?

a. Drumlin.

-->  b. Ground moraine.

c. Esker.

d. Kettles.

question_image

What are the features of the glacier erosion?

a. rock bed is found on top of the glacier

-->  b. Landforms deposited by glaciers include drumlins, kettle lakes, and eskers.

c. rock bed does not support the glacier

d. kettles are not part of glacier erosion

question_image

Where does the snow accumulation happen?

a. Ice Shelf

b. Glacier Flow

c. Sea Ice

-->  d. Antarctic Ice Sheet

question_image

Where does Ice shelf forms?

-->  a. Glacier flow

b. Icebergs

c. Continental shelf

d. Grounding line

question_image

Where in the diagram there's snow accumulation?

-->  a. Antarctic Ice Sheet

b. Ice Shelf

c. Glacier Flow

d. Icebergs

question_image

Which is located beneath the ice shelf?

-->  a. Buoyant melt plume

b. Surface crevasses

c. Icebergs

d. ESA satellite

question_image

How many satellites are in the diagram?

a. 2

b. 6

-->  c. 1

d. 4

question_image

How many of these aren't on the mountainous part?

a. 5

b. 1

-->  c. 2

d. 3

question_image

Steps of glacier formation.

a. 3

-->  b. 6

c. 2

d. 1

question_image

How do glaciers reach the melting evaporation stage?

a. snow - lateral moraine - snout

b. snow - medial moraine - melting

-->  c. snowfall - equilibrium line- medial moraine - snout - melting evaporation

d. snow - snout

question_image

How many parts are there in this picture?

-->  a. 9

b. 10

c. 7

d. 8

question_image

How many rock beds are there in the diagram?

a. 2

b. 3

c. 4

-->  d. 1

question_image

What is the zone above the equilibrium line where snow and neve are compresses and turn into glacier ice?

-->  a. Accumulation zone

b. Ice front

c. Ablation zone

d. Margin of glacier

question_image

Identify the area of a glacier where the removal of snow and ice is greater than the amount replaced.

-->  a. Ablation zone

b. Sediments

c. Accumulation zone

d. Equilibrium line

question_image

How many parts are shown in the diagram below?

a. 6

-->  b. 8

c. 5

d. 7

question_image

What are all the parts of the glacier above the equilibrium line called?

-->  a. accumulation zone

b. ice front

c. sedimentary zone

d. ablation zone

question_image

What will form when the glacier melts?

a. Zone of Plucking

b. Zone of Abrasion

-->  c. Tarn (lake)

d. Headwall

question_image

What stops the glacial ice from flowing through?

a. zone of plucking

b. zone of abrasion

-->  c. terminal moraine

d. tarn

question_image

What is located below the Headwall?

a. Terminal Moraine

b. Zone of Abrasion

-->  c. Zone of Plucking

d. Glacial Ice

question_image

From the diagram, identify the part which refers to a rounded hollow carved in the side of a mountain by a glacier.

a. arete

-->  b. cirque

c. truncated spur

d. horn

question_image

The diagram shows valleys that are caused by glacier erosion. What are these valleys called?

a. Horn

b. Truncated spur

c. Medial moraine

-->  d. Cirques

question_image

What does a glacier insist of?

-->  a. Ice

b. Soil

c. Rock

d. Air